Answer: Option (B) is the correct answer.
Step-by-step explanation:
A process in which a large nuclei of an atom splits into two small nuclei is known as a nuclear fission.
For example,
is a nuclear fission reaction.
So, there will be one reactant on bombardment with another element or particle will give more number of products in a fission reaction.
And, when two small nuclei combine together and result in the formation of a large nuclei then it is known as nuclear fusion.
For example,
is a nuclear fusion reaction.
Therefore, we can conclude that in a fission reaction, there are fewer reactants.